The Cadence Academic Network helps build strong relationships between academia and industry, and promotes the proliferation of leading-edge technologies and methodologies at universities renowned for their engineering and design excellence.

A huge knowledge exchange platform for academia to network with industry. We are looking for academic speakers to talk about their research to the industry attendees at the Academic Track at CDNLive EMEA and Silicon Valley.

Custom IC Design Forums

About the spectre pss problem

I use the old version of spectre (ver 5.10.41), when I do a vco pss analysis , I found the spectre can't catch the frequency of the vco. For example , before the pss analysis a run a tran analysis. measure the freq=1.4617G(when the vco have reach the stable state);but in the following pss analysis the freq=1.47119G; so the pnoise analysis result is not right. I don't know why the pss analysis can't catch the right frequency, and I have try nearly all the option setting, but no usefull.Can anybody tell me something about this ?

1 Reply

I'd strongly recommend using something more recent than spectre from IC5141. The release is 5.5 years old, and spectre in that release has not been maintained for a long time.

It's quite possible that the frequency that pss has found is the steady state, and that your transient is not long enough

However, you may just need to tighten your tolerances. What do you have for errpreset, and reltol in particular? Try tightening reltol to see what happens (I would strongly recommend getting a newer spectre, e.g. from MMSIM72, first).

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.